There are definitely more effective methods, just mostly not free and more time demanding.
I have a mission to get B1 French, tried Duolingo with some basic level for cca 6 months in past year. You get into the bubble that you think you are progressing but reality is, its a very narrow and not-so-useful progress if whole language knowledge is your goal - mostly passive skills and certain type of language usage that goes along with the type of exercises in Duolingo.
If you want real language knowledge, as OP mentions speaking is the hardest part (active & rapid usage of all that you know), and Duolingo doesn't prepare you for this, at all. If your goal is purely passive reading newspapers/articles, then its helpful a bit, but I would still use at least 2-3 other methods if you are even a bit serious about it.
Try talking to people after using just Duolingo, heck try writing an official letter on whatever topic. You will not just struggle, you will fail if you don't use any external help.
I've made tremendous progress with zoom meetings with professional teacher over shorter period of time. But its because I made it a priority and dedicated my time to it. And it costs quite a bit (doesn't have to, but my case is quite specific).